The present invention relates to a displacement measuring method and apparatus that install a GPS receiver in, for example, a floating body floating on the sea surface to detect the position of this floating body in order to measure displacement of the floating body, that is, variations in waves.
The kinematic positioning uses a GPS (Global Positioning System) to precisely measure the position of a receiver of the system (precisely speaking, the position of a receive antenna).
The kinematic positioning installs a receiver on a known point as a reference point while allowing another receiver to move on an unknown point, to determine a relative position between the reference point and the moving receiver, that is, a baseline vector in order to precisely measure variation components of this baseline vector.
Thus, the kinematic positioning requires the reference point. If the baseline vector is elongated, this method also requires a large amount of analysis data to be transmitted to maintain precision in measuring the baseline vector, thereby increasing technical and economical burdens.
It is thus an object of the present invention to provide a method and apparatus for measuring displacement of an object using a GPS, wherein the displacement of the object can be measured precisely without the needs for a reference point.
To attain this object, a method for measuring displacement of an object using a GPS according to the present invention is characterized by operating in measuring displacement of an object with a GPS receiver installed thereon, to measure a distance between the GPS receiver and a GPS satellite, then remove from this measured distance data, distance data corresponding to a distance to a satellite orbit to determine a variance of the GPS receiver, then determine at least three linear equations that use three-dimensional coordinates of the GPS receiver as unknown numbers, based on the variances relative to at least three GPS satellites and an azimuth and an elevation of each GPS satellite, and then solve these simultaneous equations to determine displacement of the GPS receiver corresponding to its variation component quantities on three-dimensional coordinate axes.
In addition, according to a preferred embodiment of the present invention, in the method for measuring displacement of an object, the distance data corresponding to the distance to the satellite orbit is obtained by subjecting the measured distance data to a moving averaging process, or as the distance data corresponding to the distance to the satellite orbit, satellite orbit data itself is used.
Furthermore, according to another preferred embodiment of the present invention, in the method for measuring displacement of an object, the variance of the GPS receiver is obtained by passing the measured distance data through a high pass filter to remove distance data approximate to the satellite orbit or subjecting the measured distance data to a moving averaging process based on a time window larger than or equal to a variation cycle in a measurement environment.
With the above configuration, the variances of the GPS receiver relative to the at least three GPS satellites are determined based on the measured distance data between the GPS receiver and the GPS satellites and the at least three linear equations are determined based on these variances and the azimuth and elevation of each GPS satellite so that these simultaneous equations are solved to determine the variance of the GPS receiver on the three-dimensional coordinate axes. Thus, this configuration requires no reference point in contrast to the kinematic positioning and does not require a large amount of measured data to be transmitted to the land reference point for analysis with data in the reference point. Consequently, measurement costs can be reduced and the displacement of the object can be measured precisely.
In addition, to attain the above object, the method for measuring displacement of an object using a GPS according to the present invention is characterized by operating in measuring displacement of an object with a GPS receiver installed thereon, to measure a distance between the GPS receiver and a GPS satellite, then remove from this measured distance data, distance data corresponding to a distance to a satellite orbit to determine a variance of the GPS receiver, then determine at least four linear equations that use three-dimensional coordinates of the GPS receiver as unknown numbers, based on the variances relative to at least four GPS satellites and an azimuth and an elevation of each GPS satellite, then determine differences among the at least four linear equations to obtain linear equations for at least three satellite to satellite single phase differences concerning the variance of the GPS receiver, and then solve these simultaneous equations to determine displacement of the GPS receiver corresponding to its variation component quantities on three-dimensional coordinate axes.
In addition, according to a preferred embodiment of the present invention, in the method for measuring displacement of an object, the distance data corresponding to the distance to the satellite orbit is obtained by subjecting the measured distance data to a moving averaging process, or as the distance data corresponding to the distance to the satellite orbit, satellite orbit data itself is used.
Furthermore, according to another preferred embodiment of the present invention, in the method for measuring displacement of an object, the variance of the GPS receiver is obtained by passing the measured distance data through a high pass filter to remove therefrom distance data approximate to the satellite orbit or subjecting the measured distance data to a moving averaging process based on a time window larger than or equal to a variation cycle in a measurement environment.
With the above configuration, the variance of the GPS receiver relative to the at least four GPS satellites is determined based on the measured distance data between the GPS receiver and the GPS satellites and the linear equations for the at least three satellite to satellite single phase differences are determined based on the above variances and the azimuth and elevation of each GPS satellite so that these simultaneous equations are solved to determine the variance of the GPS receiver on the three-dimensional coordinate axes. Thus, this configuration requires no reference point in contrast to the kinematic positioning and does not require a large amount of measured data to be transmitted to the land reference point for analysis with data in the reference point. Consequently, measurement costs can be reduced and the displacement of the object can be measured precisely.
To attain the above object, an apparatus for measuring displacement of an object using a GPS according to the present invention, the apparatus measuring displacement of an object with a GPS receiver installed thereon, the apparatus being characterized by comprising a distance measuring section provided in the GPS receiver for measuring distances between the GPS receiver and a GPS satellite, a variance detecting section for removing from measured distance data measured by the distance measuring section, distance data corresponding to a distance to a satellite orbit to determine a variance of the GPS receiver, and a displacement calculating section for determining at least three linear equations that use three-dimensional coordinates of the GPS receiver as unknown numbers, based on variances relative to at least three GPS satellites determined by the variance detecting section and on an azimuth and an elevation of each GPS satellite and then solving these simultaneous equations to determine displacement of the GPS receiver corresponding to its variation component quantities on three-dimensional coordinate axes.
In addition, according to a preferred embodiment of the present invention, in the apparatus for measuring displacement of an object, the distance data corresponding to the distance to the satellite orbit is obtained by subjecting the measured distance data to a moving averaging process, or as the distance data corresponding to the distance to the satellite orbit, satellite orbit data itself is used.
Furthermore, according to another preferred embodiment of the present invention, in the apparatus for measuring displacement of an object, the variance of the GPS receiver is obtained by passing the measured distance data through a high pass filter to remove therefrom distance data approximate to the satellite orbit or subjecting the measured distance data to a moving averaging process based on a time window larger than or equal to a variation cycle in a measurement environment.
With the above configuration, the variances of the GPS receiver relative to the at least three GPS satellites are determined based on the measured distance data between the GPS receiver and the GPS satellites and the at least three linear equations are determined based on these variances and the azimuth and elevation of each GPS satellite so that these simultaneous equations are solved to determine the variance of the GPS receiver on the three-dimensional coordinate axes. Thus, this configuration requires no reference point in contrast to the kinematic positioning and does not require a large amount of measured data to be transmitted to the land reference point for analysis with data in the reference point. Consequently, measurement costs can be reduced and the displacement of the object can be measured precisely.
To attain the above object, the apparatus for measuring displacement of an object using a GPS according to the present invention, the apparatus measuring displacement of an object with a GPS receiver installed thereon, the apparatus being characterized by comprising a distance measuring section provided in the GPS receiver for measuring distances between the GPS receiver and a GPS satellite, a variance detecting section for removing from measured distance data measured by the distance measuring section, distance data corresponding to a distances to a satellite orbit to determine a variance of the GPS receiver, and a displacement calculating section for determining at least four linear equations that use three-dimensional coordinates of the GPS receiver as unknown numbers, based on variances relative to at least four GPS satellites determined by the variance detecting section and on an azimuth and an elevation of each GPS satellite, determining differences among the at least four linear equations to obtain linear equations for at least three satellite to satellite single phase differences concerning the variance of the GPS receiver, and then solving these simultaneous equations to determine displacement of the GPS receiver corresponding to its variation component quantities on three-dimensional coordinate axes.
With the above configuration, the variances of the GPS receiver relative to the at least four GPS satellites are determined based on the measured distance data between the GPS receiver and the GPS satellites and the linear equations for the at least three satellite to satellite single phase differences are determined based on the above variances and the azimuth and elevation of each GPS satellite so that these simultaneous equations are solved to determine the variance of the GPS receiver on the three-dimensional coordinate axes. Thus, this configuration requires no reference point in contrast to the kinematic positioning and does not require a large amount of measured data to be transmitted to the land reference point for analysis with data in the reference point. Consequently, measurement costs can be reduced and the displacement of the object can be measured precisely.
In addition, according to a preferred embodiment of the present invention, in the apparatus for measuring displacement of an object, the distance data corresponding to the distance to the satellite orbit is obtained by subjecting the measured distance data to a moving averaging process, or as the distance data corresponding to the distance to the satellite orbit, satellite orbit data itself is used.
Furthermore, according to another preferred embodiment of the present invention, in the apparatus for measuring displacement of an object, the variance of the GPS receiver is obtained by passing the measured distance data through a high pass filter to remove therefrom distance data approximate to the satellite orbit or subjecting the measured distance data to a moving averaging process based on a time window larger than or equal to a variation cycle in a measurement environment.
With the above configuration, the variances of the GPS receiver relative to the at least four GPS satellites are determined based on the measured distance data between the GPS receiver and the GPS satellites and the linear equations for the at least three satellite to satellite single phase differences are determined based on the above variances and the azimuth and elevation of each GPS satellite so that these simultaneous equations are solved to determine the variance of the GPS receiver on the three-dimensional coordinate axes. Thus, this configuration requires no reference point in contrast to the kinematic positioning and does not require a large amount of measured data to be transmitted to the land reference point for analysis with data in the reference point. Consequently, measurement costs can be reduced and the displacement of the object can be measured precisely.
Various features and effects of the present invention will be apparent from embodiments, which will be described based on accompanying drawings.